1. Field of the Invention
This invention relates to neutralizing a static charge on sheets or webs. More particularly the invention relates to neutralizing charges on sheets or web stock that has passed through an electrophotography process. The electro-photography process tends to deposit large static charges on the sheet or web material.
2. Problem Review
In sheet or web handling it is well known that electrical charges can build up on non-conductive sheets or webs. Typically, paper stock or thin flexible plastic stock is being handled by the feeding apparatus. Motion of the feeding apparatus may create the static charges deposited upon the sheet or web being fed. These charges can cause sheet or webs to stick to the feeding apparatus thereby inhibiting the sheet handling or web handling function.
An even more serious problem occurs in the electrophotography art where paper stock or plastic transparencies are purposely given a large static charge during transfer of the image to the copy stock. Anyone familiar with use of copying equipment is well acquainted with the strong attraction between the copy sheets as they exit the copying machines. Even more serious than the inconvenience to the user of his copies sticking to one another is the problem of copies sticking and jamming automatic paper handling devices after the copy sheets move from the copier to paper handling devices such as collators.
Accordingly, one objective of the invention is to neutralize sheets or webs and particular copy sheets from a copier so that the copy sheets may be easily handled by an operator or sheet handling devices attached to a copier.
Use of coronas to produce various charge conditions on paper sheets is well known in electrophotography. Two examples include U.S. Pat. Nos. 3,237,068 and 3,717,801. These patents respectively deal with laying down a uniform charge on sheet material and reducing the charge on sheet material to assist in detaching sheet material from an electrostatic tacking plate. Neither of these patents is capable of neutralizing a sheet or a web. The support underlying the copy stock material at the corona in both of these patents can serve as a source of static charge. Further neither of these patents discusses the problem of neutralizing a copy sheet to substantially a net charge of zero.
In contrast, it is a further object of this invention to neutralize copy stock to a substantially net zero charge condition.